A grass fire in Middle Swan has forced road closures on Roe Highway with the Department of Fire and Emergency Services issuing a smoke alert for people in the area.

Roe Highway has been closed between Llyod Street and Great Northern Highway and vehicles coming from Great Northern Highway are being diverted north of the Roe Highway intersection.

Motorists travelling along Roe Highway between Toodyay Road and Middle Swan Road are warned to take extreme caution when driving through smoke and areas of low visibility.

The fire is burning in grassland north of Roe Highway and was reported at 10.50am on Saturday.

There is no threat to lives or homes but there is a lot of smoke in the area.DFES has issued a smoke alert for people travelling on Roe Highway between Toodyay Road and Middle Swan Road in Middle Swan in the City of Swan. Career and volunteer Fire and Rescue Service and Bush Fire Brigade firefighters from seven stations are on the scene and working to contain the fire. Visit www.dfes.wa.gov.au, call 1300 657 209 for further information.